In this paper excitation characteristics of the Liquid Crystal (LC) capacitive chemical and biological sensor are examined and the optimum frequency and voltage range for the sensor interface are introduced. Interdigitated capacitor has been used for the sensor capacitance measurement and two different molecular orientations, homeotropic and homogenous, have been considered. The LC sensor capac...

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used t...

The present paper describes the development of a low cost, highly accurate low capacitance measurement system that can be used over a range of 0 – 400 pF with a resolution of 1 pF. The range of capacitance may be easily altered by a simple resistance or capacitance variation of the measurement circuit. This capacitance measurement system uses quad two-input NAND Schmitt trigger circuit CD4093B ...

In this paper, the measurement of capacitance variation, of an on-chip power distribution network (PDN) due to the change of internal states of a CMOS logic circuit, is studied. A state-dependent PDNcapacitance model that explains measurement results will be also proposed. The model is composed of capacitance elements related to MOS transistors, signal and power supply wires, and substrate. Ref...

In the four previous parts of this series of articles, level measurement using a floating system, using pressure instruments, using radar waves and using ultrasonic waves were discussed. The instruments offered by Indumart company applicable for each method were also recommended. In the final part of this article, level measurement using capacitance, conductivity probes, vibration forks, therma...

A capacitor is formed when a level-sensing electrode is installed in a vessel. The metal rod of the electrode acts as one plate of the capacitor and the tank wall (or reference electrode in a non-metallic vessel) acts as the other plate. As the level of the material being measured rises, the air or gas normally surrounding the electrode is displaced by the material’s different dielectric consta...

This paper formulates a simple matrix-based solution to estimate the voltage-dependent capacitance of a weakly nonlinear device at microwave and millimeter wave frequencies. Unlike other approaches, which rely on the direct capacitance measurement at different bias voltages, the proposed technique generates a large signal model for the capacitance directly from the frequency domain measurement ...